Weekly Guide to Pregnancy: Week 8
How big is my baby?
Your baby is approximately 14-20mm (0.56 - 0.8 inches) in length and continues to grow quickly.
What changes are happening with my baby this week?
The head is large compared with the rest of the body and your baby's face is beginning to take shape (forehead, nose, cheeks, upper and lower jaw and lip and chin are forming). Eye muscles and eyelids have emerged, and by the end of the week the nasal passages have formed and the nose tip is visible. The internal and external parts of the ear are also forming. Ear openings are present, and the middle ear (hearing and balance) is there, but hearing is not yet possible for your baby.
The arms continue to grow longer, and bend at the newly formed elbow. Fingers and toes formed as notches on the hands and feet.
The valves in the heart that started forming last week can now be distinguished as the aorta and pulmonary valves. Lungs are developing and the bronchi are branching out. The skeleton has also started to form.
How is my body changing?
Your uterus is increasing in size, and while you may not have a definite or visible bulge, you will probably notice that your clothes have become tighter around the waist, breasts or thighs.
As your uterus continues to grow, you may experience feelings of tightening, or contractions. Don't be alarmed by these cramping sensations unless they are accompanied by vaginal bleeding.
What happens if I experience bleeding?
Bleeding at any time during pregnancy is seen as abnormal and medical advice should be obtained. Bleeding early on in pregnancy may be the sign of miscarriage, although slight bleeding or spotting sometimes occurs in the early months and then settles down with no adverse effect. If you have experienced spotting or bleeding, you will be advised to take it easy.
Bleeding in later pregnancy can indicate a problem with the placenta. Often the reason is not defined but you should seek medical advice so that the appropriate care can be taken.
While it is most likely that your pregnancy will progress safely and happily, you should be aware of the possibility of miscarriage and the factors that may contribute to miscarriage.
A miscarriage is defined as the loss of a pregnancy prior to 20 weeks gestation. A threatened miscarriage is diagnosed when there is vaginal bleeding in the first half of pregnancy. Bleeding may last for days or even weeks. The bleeding may or may not be associated with cramping and abdominal pain. There is no procedure or medication that can prevent a miscarriage, often a miscarriage occurs because there is a problem with the development of the baby or the mother's hormone levels. In a large proportion of cases the cause of miscarriage is unknown and as many as 1 in 3 pregnancies can miscarry. More detailed information can be found in the Miscarriage section of the Essential Baby web site.
Other Pregnancy Complications?
Although your pregnancy will probably progress safely and happily, it doesn't hurt to be aware of the pregnancy complications that some women encounter.
Special tests to consider during pregnancy.
If you are healthy, under 35 and have no hereditary or genetic problems in your family, it is unlikely you will need to undergo any of the special pregnancy tests. There are a number of special tests that may / can be performed:
if you request them
if your doctor suspects there is a problem, or
if you are over a certain age
Modern testing enables the early detection of abnormalities for those considered to be in a risk category. Early detection of serious abnormalities gives you the opportunity to decide whether or not to progress with your pregnancy. Even though you may not need, or want to undergo any special testing, it's probably a good idea to have some understanding of the tests available, what they do, and any associated risks.
Nuchal fold / nuchal translucency screening - this is an ultrasound screening assessment to detect a specific abnormality of the fetus that can be linked to Down's Syndrome. Nuchal fold / translucency screening is usually performed between 11 and 13 weeks and is becoming more routine. It is a fairly reliable, non-invasive way of assessing the risk of having a baby with Down's syndrome, and carries no risk of miscarriage. The test is conducted by measuring the appearance and amount of fluid that normally accumulates under the skin at the back of your baby's neck. The fluid accumulation tends to increase when the fetus has a chromosomal disorder. The pick-up rate is thought to be 70-80%, depending on your age.
Rhesus testing - if your blood type has a negative Rhesus factor, you will need extra blood tests during pregnancy to check for the possibility of antibody formation. Your baby's blood group is then checked at birth and if it has a positive Rhesus factor, you will need an injection of Anti D gamma globulin to stop the risk of antibodies forming that may affect future pregnancies.
Chorionic villus sampling (CVS) - this test may be performed between 10 and 12 weeks to test for genetic / chromosomal abnormalities such as Down's syndrome, sickle-cell anaemia, thalassaemia, cystic fibrosis, Huntingdon's chorea, muscular dystrophy and haemophilia. One of the advantages of CVS testing is that it can be done before it is possible to do an amniocentesis, as the chorionic tissue develops earlier than the amniotic fluid, and is genetically identical to the baby. One of the disadvantages is the risk of miscarriage. When CVS testing is performed by an experienced doctor, the risk of miscarriage in one in 50. These stats include miscarriages that may have occurred anyway without the test. The test is performed by passing a tube through the vagina into the uterus, or a needle through the abdominal wall into the uterus. Some of the chorionic tissue that surrounds the baby is then removed by suction for testing.
Amniocentesis - this test can be performed between Week 14 and Week 16 to test for chromosomal abnormalities, inherited disorders, fetal maturity and neural tube defects such as spina bifida. It involves passing a hollow needle through the Mother's abdomen into the amniotic sac to extract a small amount of amniotic fluid (the fluid inside the amniotic sac in which the baby floats). The risk of miscarriage from amniocentesis is lower than CVS testing. When an experienced doctor performs an amnio, the risk of miscarriage is one in 100 or lower. These stats include miscarriages that may have occurred anyway without the test. Common symptoms after the test include tightening of the uterus and soreness. Women are advised to take it easy for a few days after the test.
AFP Test - this is a blood test that may be performed at around Week 16 to screen for an increased risk of neural tube defect, or spina bifida (an abnormality in the formation of the spine). The test measures the level of alpha-fetoprotein, a protein manufactured in the baby's liver, which then passes into your bloodstream. A high level of AFP in your blood can indicate a neural tube defect. Too much AFP in the blood occurs in three in 100 women, but don't panic because there can also be other reasons for high AFP levels. It might mean that you are having twins, or that your pregnancy is further along than you thought. It doesn't necessarily mean the baby is affected, but it will probably be suggested that you have an amniocentesis for more definite results. If, on the other hand, your AFP level is very low (this happens in less than five in 100 pregnancies), the levels of two other hormones may also be measured. This is called a triple screening (see below).
Triple Screen Test / The Bart's Test - this test is a triple blood test that can be performed at around Week 16 to screen maternal blood for evidence of an increased risk of Down's syndrome or other chromosomal abnormalities. The test measures AFP, hCG and oestriol levels. If the result shows a high risk then you can decide whether to have an amniocentesis.
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